I would like to send a transactional email with unsubscribe/opt-out url included. It usually gets triggered by civirules when the person gets added to a group. when email is sent the unsubscribe url does not render. civirules have suggested I hardcode the link. I have tried https://example.com/civicrm/mailing/unsubscribe?reset=1&cid={contact.contact_id}&{contact.checksum}
But with this link I get "Missing Parameters" errors. What is missing here? thanks